Why do roof slabs require reinforcement?

• A. Temperature changes, Safety, Shrinkage
• B. Temperature changes and Shrinkage
• C. Safety and Cost
• D. Only Temperature changes

Answer: (A)

Roof slabs are made of concrete, which handles compression well but has poor tensile strength. When a slab carries loads, it bends and develops tensile stresses on the bottom surface. Temperature changes cause the concrete to expand and contract, and the material also shrinks as it cures and dries. Both these effects create cracking if the concrete is left to resist tension on its own. Reinforcement, placed as steel bars, becomes the primary tensile resistance, keeping cracks tight and the slab behaving as a single, continuous member. This improves safety by preventing crack widening that could weaken the structure, spread loads more evenly, and reduce durability against moisture and environmental effects. In short, reinforcement is needed to control cracks from temperature changes and shrinkage while enhancing the overall safety and performance of the roof slab.